Former National Treasury director-general Lungisa Fuzile told the state capture inquiry on Monday that if former president Jacob Zuma’s proposed 'nuclear deal' had gone through, government would have breached the expenditure ceiling it set for itself.

Fuzile, who is testifying before the commission for the second time, described a presentation that National Treasury conducted into the fiscal implications of the nuclear build project.

The nuclear build programme was dealt a blow in 2018 by the Cape Town high court after Earthlife Africa and the Southern Africa Faith-Communities' Environmental Institute successfully challenged the way in which the state determined the country's nuclear power needs.

The plan would have seen South Africa purchasing 9,600 megawatts of extra nuclear power from the Russians at a cost of about R1-trillion.

"We modelled two scenarios. We did the maximum amount that was contemplated which was 9.6 gigawatts, then we also did a smaller scenario predicated on a modularised approach to nuclear which was 2.4 gigawatts. We made assumptions about the costs per kw. We made assumptions about GDP growth," Fuzile said.

He said Treasury’s assumptions were based on 2% GDP growth per annum - a forecast which South Africa has not been able to accomplish.

"It would have caused our country to breach the expenditure ceiling that government had set for itself," said Fuzile.

Quoting public enterprises minister Pravin Gordhan, who was finance minister when the deal was proposed, Fuzile said that should anything go wrong it would make the arms deal "look like a Sunday school picnic".